I'm not much of an Opera-buff, but I do like the DigiFi's Opera wireless headphones.

I'm not certain whether you can tell from this photo, but the Opera is designed to go around the back of your head. You can then plug the wireless transmitter into your iPod, and you will hear excellent wireless sound. The Opera uses Kleer technology, a wireless transmission technology that has higher specs than Bluetooth.

If wireless sound is important to you, then you should be able to purchase the Opera for about $98.

Source